Stack-up assembly

ABSTRACT

A stack-up pump is provided with a pressure generating area ported through a pressure plate and a separator plate to a valve plate, the separator plate contacting the pressure plate on one side and open to high pressure channels on the other side whereby the separator plate is biased against the pressure plate and the pressure plate in turn against the pressure generating rotor cavity to maintain a seal. To prevent the separator plate from pressing against the pressure plate with sufficient force to bow the pressure plate and seize the rotor, the pressure plate is relieved in areas under the separator plate.

Waited States Patent 1191 Carlson .Fan. 22, 1974 [54] STACK-UP ASSEMBLY [75] Inventor: Robert Edward Carlson, Livonia, f' crqyle Mich. -Y9HEflmVj9h .J- vrabh n Attorney, Agent, or F irm-Hill, Sherman, Meroni, [73] Assignee: TRW Inc., Cleveland, Ohio Gross & Si [22] Filed: July 7, 1972 57 ABSTRACT [21] Appl. No.: 269,766 A stack-up pump is provided with a pressure generating area ported through a pressure plate and a separa- 52] us. (:1. 418/133 tor plate to a valve plate, the separator plate contact- 51 1111. c1...... Flc 19/08, F030 3/00, F040 /00 ing the pressure plate on one Side and p to high [58] Field of Search 418/131, 133; 417/300 Pressure channels on the other Side whereby the p rator plate is biased against the pressure plate and the [56] Ref r n Cit d pressure plate in turn against the pressure generating UNITED STATES PATENTS rotor cavity to maintain a seal. To prevent the separator plate from pressing against the pressure plate with sufficient force to bow the pressure plate and seize the 3200752 8/1965 Clark et 417/300 rotor, the pressure plate is relieved in areas under the 3,549,288 12/1970 Nichols et al... 418/133 sepamof P 2,3l2,89l 3/1943 Ferris 4. 418/133 3,057,304 10/1962 Rohde 418/133 7 Clam, 5 Drawmg 39 1/ 38 F3. 01 II II 42 29 H371 30 17 26 I I 34 a! 1 I 4 :1 ,a 33 60 12 I I: I 65 0 ,1

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PATENTEUJAR 22 1914 Fig. 1

PH PH PH PH PH 37 35 FZM STACK-UP ASSEMBLY BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to pumps and more particularly to a rotary slipper type pump.

2. Prior Art Rotary slipper pumps are well known and have found use in numerous embodiments. A particularly useful embodiment for such pumps, and one in which the instant invention will be described, is in automotive power steering pumps.

Such pumps include a pumping chamber defining member, commonly a ring with a varying radius inner diameter. Into this chamber-defining member is received a rotor having a plurality of radial slots therein which receive slippers disposed for radial movement. As the rotor rotates within the chamber, the slippers move radially of the slots and the chambers defined between the inner diameter of the chamber-defining member and the outer diameter of the rotor and between adjacent slippers changes to compress fluid received between adjacent slippers. The compressed fluid is ported through an end plate lying on one or both ends of the chamber-defining member and exits as a higher pressure fluid. It has been known, and it is common, to provide a separator plate adjacent one of the end plates. The separator plate has orifices therethrough and the high pressure fluid passes through the orifices to chambers defined in a valve plate or closure plate located on the other side of the separator plate. These chambers then become high pressure channels and act to press the separator plate against the end plates. The end plates in such instances may be referred to as pressure plates in that they are forced against the side walls of the chamber-defining member to create a tight seal. Because their opposed faces, which define the side walls of the pumping chamber, are in contact with both low and high pressure areas of the pumping chamber, the presence of a high pressure on the opposite side pressure balances them into maintaining a seal with the chamber-defining member.

However, the pump pressure can be extremely high and can therefore press the separator plate against the end plate or pressure plate to such a degree as to cause a bending or bowing in the center of the pressure plate which is not supported by contact with the ring-like chamber-defining member. In such instances, the pressure plate can be bowed into contact with the rotor or the slippers to an extent sufficient to increase the degree of torque necessary to rotate the rotor; In certain instances, this pressure against the rotor can be so excessive as to cause seizing of the rotor.

A pump of the type commonly used for automotive power steering pumps is disclosed in the U.S. Fat. to H. M. Clark et al., No. 3,200,752 issued Aug. 17, 1965.

Numerous attempts have been made to reduce or eliminate the friction or seizing problem caused by pressing the pressure plate against the rotor. Some such attempts have relied upon the use of pressure relieving porting to other areas of the pump, while others have considered moving the high pressure receiving grooves. All of these solutions are cumbersome and expensive, and may have the disadvantage of decreasing the effectiveness and ease of assembly of the pump. It would therefore be an advance in,the art if a simple, economic, non-complicated construction could be found which would eliminate this problem.

SUMMARY OF THE INVENTION My solution meets all of the above criteria. The problem is caused solely by the fact that the high pressure exists on one side of the separator plate, the other side of which is in contact with one face of the pressure plate, and the other side of the pressure plate is faced with both high and low and transitional pressure zones. Therefore, the separator plate is pressed against the pressure plate and as the pressure on the separator plate increases, the pressure on the pressure plate must increase. This entire problem is eliminated if the separator plate does not contact the pressure plate. However, since the separator plate serves a function in closing off communication between the inlet and the outlet areas of the pressure plate, the separator plate must contact the side face of the pressure plate in sealing relationship.

Because of this, it has not been thought to solve the bending problem by separating the separator plate and the pressure plate. However, I have determined that it is only necessary for the separator plate to contact the pressure plate in those areas where a seal must be created between the high pressure and the low pressure plate. I have therefore found it possible to relieve areas of the pressure plate between the low pressure inlets. These relief areas lie in the center portion of the pressure plate, which is the portion which would be bent into contact with the rotor. By relieving these portions underneath the separator plate, a space is provided which the separator plate may bend into without acting against the pressure plate. Further, because the outer diameter areas of the pressure plate are supported by contact with the chamber-defining member, there can be no inward bending in these areas. The use of my relief areas allows the system to experience a much greater pressure differential between the outer faces of the pressure plate and separator plate without causing a bending of the pressure plate.

It is therefore an object of this invention to provide an improved rotary pump.

It is a further object of this invention to provide an improved rotary pump wherein the rotor end plate will not be pressure forced into contact with the rotor to an extent sufficient to sieze the rotor.

It is a more specific object of this invention to provide a rotary slipper pump wherein the rotor is received between end plates centrally of a chamber-defining member, the end plates are pressure-biased against the chamber-defining memberv and the rotor to provide a sealed pressure chamber and means are provided on at least one end plate to prevent high pressure acting against the end plate or against the separator plate in contact with the end plate from causing the end plate to bend into tighter contact with the rotor.

It is yet another and more specific object of this invention to provide a rotary slipper pump with a stackup of parts including in axial relation to a bottom pressure plate, a chamber-defining ring member, a rotor received within the interior of the ring member, a top pressure plate, a separator plate, and a valve plate with the top pressure plate having a relieved area below the separator plate to prevent the separator plate from bowing the top pressure plate into seizing contact with the rotor.

BRIEF DESCRIPTION OF THE DRAWINGS Other objects, features and advantages of the invention will be readily apparent from the following description of certain preferred embodiments thereof, taken in conjunction with the accompanying drawings, although variations and modifications may be effected without departing from the spirit and scope of the novel concepts of the disclosure, and in which:

FIG. 1 is a cross-sectional view of a pump incorporating the teachings of this invention;

FIG. 2 is a cross-sectional view taken along the lines IIII of FIG. 1, illustrating the separator plate;

FIG. 3 is a plan view of the one surface of the top pressure plate;

FIG. 4 is a plan view of the other surface of the top pressure plate; and

FIG. 5 is a simplified view of a pump equipped with the invention and illustrating force vectors.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 5 illustrates the forces at work in a pump of the type in which this invention may be practised. The pump includes elements received in a pressure housing 90. Disposed within the pressure housing is a pumping chamber defining member 91 which has a continuous wall 92 surrounding a cavity, the wall being formed as a continuous closed curve having varying inner diameters. Disposed within the pumping chamber defining member is a rotor 93. The chamber 94 is closed at either end by pressure plates 95 and 96. The lower pressure plate 95 is generally bottomed against a housing closure member, while the upper pressure plate 96 has its outer surface bottomed against a separator plate 97 which in turn has its outer surface bottomed against a valve body 98 received in the pressure housing 90. Pressure developed in the chamber 94 is ported through at least the upper pressure plate and separator plate to the interior of the valve body and also to the interior of the pressure housing exterior of the valve body. The pressure thus developed, represented by the arrows P acts to force the valve body against the separator plate 97. This pressure P representing a hydraulic pressure, is transformed to a mechanical pressure at the interface between the valve body and the separator plate as indicated by the arrows F The mechanical force F acting against the separator plate, will be transmitted directly against the pressure plate if the two plates mate completely. This pressure can tend to bow the pressure plate into the cavity 94 to the extent that there is an allowed end clearance 99. This can bring the pressure plate into contact with the rotor.

This invention overcomes this problem by providing a relief area 100 in a mating surface between the separator plate and upper pressure plate. The relief area in FIG. 5 is illustrated as being in the upper pressure plate and is centrally disposed thereof. Thus, the mechanical force P, will be transmitted through the upper pressure plate at its periphery against the body of the pumping chamber defining member 92 as indicated by the arrows F Since at this point, the upper pressure plate 96 is supported directly by the wall of the pumping chamber defining member, the tendency of the upper pressure plate to bow inwardly towards the rotor in the central sections is minimized. Although the invention will hereinafter be disclosed in connection with a specific pump embodiment which utilizes a valve body separator plate and upper pressure plate, it is to be understood that the invention can be practised in other pumps which may eliminate one or more of these elements or which may substitute others in their place. For example, a pump could be designed where the valve body acts directly against the upper pressure plate. In such an instance, the forces would still be the same inasmuch as the force F would act against the upper pressure plate without the intermediary of the separator plate. This could still, however, cause the bowing of the upper pressure plate. It is further to be understood that although the arrows P are described as hydraulic pressure against the valve body, in those cases where the valve body has hollow channels open to the separator plate, as in the embodiment hereinafter described, that some hydraulic pressure will be developed directly against the separator plate from the high pressure cavities within the valve body.

FIG. 1' illustrates a specific embodiment of this invention and shows an automotive power steering pump which includes a cup-shaped housing member 11 closed at its open end by a cap member 12 having a central bore 13 therethrough. The bore 13 may include a sleeve bearing 14 and a shaft 15 is supported through the closure 12 in the opening 13. The external end of the shaft 17 may be fitted with a driving means such as, by way of example, a pulley wheel 18 which may be operated by the vehicle engine drive belt.

The pumping section 20 of the pump 10 includes, in axial stacked-up relation, the closure cap 12, a first or bottom pressure plate 21, a chamber-defining ring member 22 which has a lobed or varying radius inner diameter 23 and which surrounds a rotor 24 carrying a plurality of slippers 25 in radial slots in the rotor, the slippers being positioned for radial and rocking movement in the grooves of the rotor and being expanded into contact with the inner diameter 23 by springs 26. The rotor is splined onto the shaft 15.

The end 29 of the chamber-defining member 22 remote from the first pressure plate 21 is closed by a second pressure plate 30. The opposite side of the pressure plate 30 from the chamber-defining member is contacted by a separator plate 31 which in turn has its outer surface 32 contacted by a valve plate 33. An inner cup-shaped housing 34 has a flanged open end 35 riding on a radial face 36 which extends radially outwardly from the pressure plate contacting face 37 of the end cap 12. The inner cup-shaped housing 34 encloses the stacked first pressure plate 21, the pumping chamber defining member 22, and its enclosed rotor 24 and slippers 25, the second pressure plate 30, separator plate 31 and valve plate 33 while providing an area 37 beyond the valve plate 33. The entire assemblage is received within the cup-shaped housing 11 which contacts an outer diameter surface 38 of the end cap 12. Seals 39 may be interposed between the end cap 12 and the cup-shaped housing 11 and gasket seals 40 may be interposed between the radial face 36 and the flange 35 of the inner cup-shaped housing 34.

In addition, a seal 42 is interposed between the inner cup-shaped housing 34 and the outer diameter surface of the valve plate 33 which divides the inner cupshaped housing into a high pressure area 37 and a lower pressure area 44 radially outwardly of the pressure plates and pumping chamber.

A discharge outlets 45 is communicated through the outer 11 and inner cup-shaped housings 34 to 'an area 46 interior of the valve plate 33. A port 47 communicates the area 37 to the conduit 48 between the valve plate and the outlets 45. A return 49 communicates the exterior to the low pressure area 50 between the outer 11 and inner 34 cup-shaped housings and a fill cap 51 is also provided communicating to the area 50. The area 50 is also communicated to the area 44 to provide a flow of low-pressure fluid to the area 44.

In operation, the area 50 is maintained in a flooded state with low-pressure fluid which is ported through the first and second pressure plates 21 and 30 to low pressure areas of the pumping chamber inwardly of the pumping chamber defining member 22. As the slippers move circumferentially in the pumping chamber, the pressure of the fluid is increased and then ported again through the pressure plates to channel 60 in the valve plate. The channel 60 opens to a valve area 61 which in turn is communicated to the discharge conduit 48 through a port 62.

The channels 60 are open to the separator plate 32 which in turn has discharge ports to open to the outlet openings in the pressure plates. The outlet openings of the first pressure plate 21 are in communication with outlet openings in the second pressure plate through axially extending channels in the ring-shaped chamberdefining member 22.

The presence of the high-pressure channels on the outside face 32 of the separator plate 31 forces the separator plate against the outside face 58 of the second pressure plate. Because the inside face 59 of the second pressure plate is alternately exposed to high and low pressure areas of the pumping chamber, pressure dif ferential exists between the outside face 32 of the separator plate 31 and the inside face 59 of the pressure plate 30. This pressure differential biases the pressure plate against the radial face of the chamber-defining member 22 to maintain a sealing interface. In addition, the opposite radial face of the chamber-defining member 22 is forced against the first pressure plate 21 to maintain a sealing face there and the pressure plate 21 is forced against the face 37 of the end cap 12. In this manner, the entire assembly is pressed together. Because of the porting of the high pressure fluid through the port 47 to the area 37, the pressure also acts against the outside face 65 of the valve plate which has a greater surface area than the channels 60, whereby the valve plate is pressed against the separator plate 31.

In operation, the pressure in the channels 60 can become quite large. At times this pressure can become so large as to press the separator plate 31 against the second pressure plate 30 to an extent sufficient to bow or bend the second pressure plate 30 inwardly towards the rotor. Because the outer peripheral areas of the pressure plate 30 are supported on the radial face of the chamber-defining member, the central section of the pressure plate will be pressed into contact with the rotor and slippers. When this pressure becomes excessive, it can increase frictional contact between the pressure plate and the rotating rotor and slippers to an extent sufficient to adversely affect the operation of the pump and, in extreme circumstances, can cause the rotor to seize. It is a primary object of this invention to prevent this from occurring.

FIG. 3 illustrates the second pressure plate 30 and is a plan view of the face 58 thereof which contacts the separator plate 31 illustrated in FIG. 2.

FIG. 4 is a plan view of the pressure plate 30 illustrating the face 59 and the back side of the view of FIG. 3. The separator plate 30 includes inlet openings circumferentially spaced from one another and open to the periphery 71 of the pressure plate. Minor inlet openings 72 are disposed radially inwardly of the opening 70 and are in communication therewith through a reduced axial thickness area 73. The minor inlets 72 communicate to the slipper receiving grooves in the rotor. circumferentially spaced from the inlets 70 are outlet openings 74 which are aligned with the highpressure portions of the chambers defined by the lobed or varying radius inner diameter of the chamberdefining member and the outer diameter of the rotor. Minor outlets 75 are disposed radially inwardly of the outlet 74 and communicate to the bottoms of the slipper receiving grooves. The outlets 74 and 75 are ported to the discharge ports of the separator plate 31 which in turn is open to the channels 60 in the valve plate. The separator plate contacts the surface 58 of the pressure plate and separates the inlet openings and outlet openings and is pressed against the face 58 to maintain the separation of the openings.

In order to prevent the pressure of the contact between the separator plate and the pressure plate from becoming sufficiently large in the central areas of the pressure plate to bow it into contact with the rotor, I have recessed portions of the surface 58 of the pressure plate. The portions which I have chosen to recess are those areas which do not include or surround the high pressure outlet openings and the dowel pin receiving openings 86 which align the members. As can be seen from FIG. 3, two circumferentially spaced lands 87 and 88 are therefore provided which are raised above the recessed area 85. The lands 87, 88 are diametrically opposed from one another and contain the opposed outlet 74 and minor outlet 75 as well as the dowel pin openings 86. The remainder of the surface 58 is recessed which results in a communication of the inlet openings 72 and 73 with each other across the diameter of the pressure plate.

By providing the recess 85, I have provided an area into which the separator plate may bow without contacting the surface of the pressure plate. Thus, in periods of extreme pressure differential, the separator plate 31 may bow inwardly towards the rotor without contacting the central section of the pressure plate. Therefore, the pressure plate will not be forced against the rotor in the central section. At the same time, the separator plate is maintained in continuous contact with peripheral areas of the pressure plate and particularly in the raised areas 87, 88.

It can therefore be seen from the above that my invention provides a stack-up slipper pump wherein a recess area is provided between the pressure plate and the separator plate to prevent the separator plate from being forced into contact with the outer surface of the pressure plate to an extent sufficient to bend the pressure plate into excessive seizing.

Although minor modifications might be suggested by those versed in the art, it should be understood that 1 wish to embody within the scope of the patent warranted hereon all such modifications as reasonably and properly come within the scope of our contribution to the art.

I claim as my invention:

1. A fluid pressure loaded pump having a stack of pump components loaded by an end plate and including a member defining a pumping chamber with fluid inlet and outlet passages, a rotor in the pumping chamber, a pressure plate bottomed on said member and covering the rotor, a separator plate overlying the pressure plate receiving the end plate thereagainst, said end plate having outlet channels, said pressure and separator plates having outlet ports registering with said channels, and said pressure and separator plates having surfaces in sealed mated engagement around the ports thereof together with a gap between the separator and pressure plates in the central portion thereof vented to the fluid inlet effective to prevent bowing of the pressure plate against the rotor under fluid pressure loading of the stack of components.

2. In a pump having a stack of pressure loaded pump components including a member defining a pump chamber, a pump rotor rotatably mounted in said chamber, a pressure plate bottomed on the member providing an end wall for the pump chamber and having inlet and outlet ports conveying fluid to and from the pump chamber, a separator plate overlying the pressure plate having outlet ports registering with the outlet ports of the pressure plate, and an end plate bottomed on the separator plate having outlet ports communicating with the outlet ports of said separator plate, the improvements of land areas surrounding the outlet ports of the pressure plate seated on the separator plate around the outlet ports of the separator plate to seal the outlet ports from the inlet ports and a gap between the separator and pressure plates communicating with the inlet ports of the pressure plate and effective to prevent deformation of the pressure plate against the rotor under pressures developed by the pump.

3. The pump of claim 2 wherein the land areas surrounding the outlet ports of the pressure plate are separated by a recessed area between the land areas.

4. The pump of claim pressure wherein the recessed area spans the center of the present plate.

5. The pump of claim 2 wherein the end plate has outlet openings communicating with the outlet ports of the separator plate, and the recess is formed in the pressure plate.

6. The pump of claim 5 wherein the pressure plate is thicker than the separator plate.

7. Arotary pump comprising a housing, and end cap for the housing, a shaft rotatably supported in said end cap extending into the housing, an axial stack-up of pump parts in said housing including a bottom pressure plate bottomed on the end cap, a pumping chamber defining ring bottomed on the bottom pressure plate, a pump rotor in said ring coupled to said shaft, a second pressure plate bottomed on said ring, a separator plate bottomed on said second pressure plate, and a valve plate with an outlet passage bottomed on said separator plate, slippers carried by said rotor riding in said ring, seal means between the valve plate and housing separating the interior of the housing into an inlet chamber and a pressure chamber, said second pressure plate having inlets joining the inlet chamber of the housing with the interior of the chamber defining ring to supply fluid to be pumped by said slippers, said second pressure plate and separator plate having outlet ports joining the interior of the chamber defining ring with the outlet passage of the valve plate, means venting said pressure chamber in said housing to pressured fluid from the pump to act on the valve plate for axially biasing the stack of pump parts against the end cap of the housing, and said second pressure plate having land areas surrounding the outlet ports thereof mating with the separator plate around the outlet ports thereof together with a central relieved area between said land areas communicating with the inlets of the second pressure plate and providing a gap between the central portions of the separator and pressure plates to prevent any deformation of the separator plate under excessive fluid pressure loads from bowing the central portion of the pressure plate against said rotor whereby the stack of pump parts is pressure-loaded to maintain seals between the components in the stack and binding of the rotor by fluid pressure acting on the stack is eliminated. 

1. A fluid pressure loaded pump having a stack of pump components loaded by an end plate and including a member defining a pumping chamber with fluid inlet and outlet passages, a rotor in the pumping chamber, a pressure plate bottomed on said member and covering the rotor, a separator plate overlying the pressure plate receiving the end plate thereagainst, said end plate having outlet channels, said pressure and separator plates having outlet ports registering with said channels, and said pressure and separator plates having surfaces in sealed mated engagement around the ports thereof together with a gap between the separator and pressure plates in the central portion thereof vented to the fluid inlet effective to prevent bowing of the pressure plate against the rotor under fluid pressure loading of the stack of components.
 2. In a pump having a stack of pressure loaded pump components including a member defining a pump chamber, a pump rotor rotatably mounted in said chamber, a pressure plate bottomed on the member providing an end wall for the pump chamber and having inlet and outlet ports conveying fluid to and from the pump chamber, a separator plate overlying the pressure plate having outlet ports registering with the outlet ports of the pressure plate, and an end plate bottomed on the separator plate having outlet ports communicating with the outlet ports of said separator plate, the improvements of land areas surrounding the outlet ports of the pressure plate seated on the separator plate around the outlet ports of the separator plate to seal the outlet ports from the inlet ports and a gap between the separator and pressure plates communicating with the inlet ports of the pressure plate and effective to prevent deformation of the pressure plate against the rotor under pressures developed by the pump.
 3. The pump of claim 2 wherein the land areas surrounding the outlet ports of the pressure plate are separated by a recessed area between the land areas.
 4. The pump of claim pressure wherein the recessed area spans the center of the present plate.
 5. The pump of claim 2 wherein the end plate has outlet openings communicating with the outlet ports of the separator plate, anD the recess is formed in the pressure plate.
 6. The pump of claim 5 wherein the pressure plate is thicker than the separator plate.
 7. A rotary pump comprising a housing, and end cap for the housing, a shaft rotatably supported in said end cap extending into the housing, an axial stack-up of pump parts in said housing including a bottom pressure plate bottomed on the end cap, a pumping chamber defining ring bottomed on the bottom pressure plate, a pump rotor in said ring coupled to said shaft, a second pressure plate bottomed on said ring, a separator plate bottomed on said second pressure plate, and a valve plate with an outlet passage bottomed on said separator plate, slippers carried by said rotor riding in said ring, seal means between the valve plate and housing separating the interior of the housing into an inlet chamber and a pressure chamber, said second pressure plate having inlets joining the inlet chamber of the housing with the interior of the chamber defining ring to supply fluid to be pumped by said slippers, said second pressure plate and separator plate having outlet ports joining the interior of the chamber defining ring with the outlet passage of the valve plate, means venting said pressure chamber in said housing to pressured fluid from the pump to act on the valve plate for axially biasing the stack of pump parts against the end cap of the housing, and said second pressure plate having land areas surrounding the outlet ports thereof mating with the separator plate around the outlet ports thereof together with a central relieved area between said land areas communicating with the inlets of the second pressure plate and providing a gap between the central portions of the separator and pressure plates to prevent any deformation of the separator plate under excessive fluid pressure loads from bowing the central portion of the pressure plate against said rotor whereby the stack of pump parts is pressure-loaded to maintain seals between the components in the stack and binding of the rotor by fluid pressure acting on the stack is eliminated. 